Quantum dot ink and quantum dot light conversion element, display device

Abstract

The application relates to the field of inkjet printing technology and discloses a quantum dot ink, which comprises quantum dots, siloxane, a reactive coupling agent containing C=C bonds and Si-O bonds, the surface of the quantum dots has organic chain segments, and the organic chain segments are linked with active functional groups capable of being photocured. The quantum dot ink of the application adds siloxane in the quantum dot ink, in the process of curing into a film after inkjet printing, the siloxane generates polysiloxane microspheres through chemical reaction, the polysiloxane microspheres can be used as a light diffuser to improve the optical performance of the quantum dot ink, so that in the quantum dot light conversion element, the polysiloxane microspheres can scatter the light of the backlight blue light, reduce the transmission of the blue light, and make more blue light be absorbed by the quantum dots, thereby improving the light brightness of the quantum dot light conversion element; the addition of the reactive coupling agent makes the dispersibility of the quantum dots and the formed polysiloxane microspheres in the ink very good, thereby reducing the roughness of the film surface of the quantum dot light conversion element.

Description

Technical Field

[0001] This invention belongs to the field of inkjet printing technology, and particularly relates to a quantum dot ink, a quantum dot light conversion element, and a display device. Background Technology

[0002] Quantum dots, also known as semiconductor nanocrystals, are a novel type of semiconductor nanomaterial with sizes ranging from 1 to 10 nm. Due to quantum size and dielectric confinement effects, they possess unique photoluminescence (PL) and electroluminescence (EL) properties. Compared to traditional organic fluorescent dyes, quantum dots exhibit superior optical properties such as high quantum yield, high photochemical stability, resistance to photolysis, broad excitation and narrow emission range, high color purity, and the ability to adjust the emitted color by controlling the size of the luminescent nanoparticles. They hold broad application prospects in display technology, with quantum dot light conversion films being one of the most promising applications and a current research hotspot.

[0003] Currently, quantum dot light conversion elements are typically fabricated using inkjet printing. The advantage of inkjet printing lies in its ability to control the position and size of the quantum dot ink droplets, enabling the printing of a film. Existing quantum dot inks are prepared by dissolving quantum dots in a resin system. These inks are then used to create quantum dot light conversion elements through printing and curing. However, to enhance optical performance, light-diffusing particles are usually added to the quantum dot ink. Because these particles are relatively large, they can cause printing irregularities. Even if the particles are dispersed in the ink, they tend to settle quickly, clogging the printhead.

[0004] Therefore, there is an urgent need to develop a quantum dot ink that prints smoothly, has high luminous efficiency, and good stability. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a quantum dot ink, a quantum dot light conversion element, and a display device, which can obtain a quantum dot light conversion element with high optical performance and a relatively flat film surface without adding light diffusing particles to the ink.

[0006] According to a first aspect of the present invention, a quantum dot ink is provided, comprising quantum dots, a siloxane, a reactive coupling agent containing C=C bonds and Si-O bonds, wherein the surface of the quantum dots has organic segments linked to photocurable active functional groups, and the reactive coupling agent is capable of being linked to the siloxane and the photocurable active functional groups.

[0007] This invention adds siloxane to quantum dot ink. During the inkjet printing and curing process, the siloxane reacts chemically to form polysiloxane microspheres. These microspheres act as light diffusing agents, enhancing the optical performance of the quantum dot ink. Consequently, in the quantum dot light conversion element formed from this ink, the microspheres scatter the blue light from the backlight, reducing the amount of transmitted blue light and allowing more blue light to be absorbed by the quantum dots, thus increasing the brightness of the light output. After curing, the siloxane reacts to form light-diffusing polysiloxane microspheres, eliminating the need to add light-diffusing particles to the ink. Furthermore, the polysiloxane microspheres are organic, have low density, and are not prone to settling, avoiding the problems caused by the addition of light-diffusing particles, such as short-term settling, difficulty in preservation, and printhead clogging. This significantly improves the brightness of the light output of the quantum dot light conversion element.

[0008] Furthermore, this invention adds a reactive coupling agent containing C=C and Si-O bonds to the quantum dot ink. Since the organic segments on the surface of the quantum dots are linked with photocurable active functional groups, the photocurable active functional groups crosslink with the C=C bonds of the coupling agent, and the Si-O bonds form chemical bonds with the siloxane. This results in excellent dispersion of the quantum dots and the formed polysiloxane microspheres in the ink, thereby reducing the surface roughness of the quantum dot light conversion element prepared from the quantum dot ink.

[0009] As a preferred embodiment of the aforementioned quantum dot ink, acrylate monomers are also included;

[0010] Preferably, it also includes a photoinitiator;

[0011] Preferably, it also includes a polymerization inhibitor.

[0012] Acrylic monomers are used to disperse and dissolve quantum dots, siloxanes, and reactive coupling agents; photoinitiators play an initiation role in the ink curing process; polymerization inhibitors are used to prevent the aggregation of quantum dots, siloxanes, and reactive coupling agents, resulting in excellent overall dispersion of quantum dot inks and easy storage.

[0013] In this invention, the photoinitiator includes at least one of the following: 2,4,6-trimethylbenzoyl-diphenylphosphine, 2-hydroxy-2-methyl-1-phenylpropanone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, benzoin, benzoin dimethyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, benzoin benzoate, benzophenone, 2,4-dihydroxybenzophenone, and micriton.

[0014] In this invention, the polymerization inhibitor includes at least one of the following: butylated hydroxytoluene, hydroquinone, p-methoxyphenol, di-tert-butyl-p-cresol, pyrogallol, tert-butylcatechol, benzoquinone, 4,4'-thiobis(3-methyl-6-tert-butylbenzoic acid), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), N-nitrosophenylhydroxylamine cerium salt, phenothiazine, phenotoxazine, 4-methoxynaphthol, 2,2,6,6-tetramethylpiperidine-1-oxy radical, 2,2,6,6-tetramethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy radical, nitrobenzene, and dimethylaniline.

[0015] As a preferred embodiment of the aforementioned quantum dot ink, the photocurable active functional group includes substituted or unsubstituted propylene groups; preferably, the photocurable active functional group is selected from acrylate monomers. That is, the photocurable active functional group contains carbon-carbon double bonds. Under ultraviolet light irradiation and the action of a photoinitiator, the photocurable active functional group on the surface of the quantum dots crosslinks with the acrylate monomers, forming chemical bonds between the quantum dots and the acrylate monomers. The bonds are strong, resulting in good film uniformity. Furthermore, because the bonds are chemically bonded, the quantum dots will not precipitate from the quantum dot film at high temperatures, ensuring the high luminous efficiency of the quantum dot film.

[0016] As a preferred embodiment of the aforementioned quantum dot ink, the reactive coupling agent includes an unsaturated silane coupling agent;

[0017] Preferably, the unsaturated silane coupling agent is selected from methylvinyldimethoxysilane, methacryloyloxyethoxytrimethylsilane, methacryloyloxypropyltris(trimethylsiloxane)silane, γ-methacryloyloxypropyltrimethoxysilane, 1-methoxy-2-methyl-1-(trimethylsiloxy)propene, 3-(methacryloyloxy)propyltrimethoxysilane, 3-(isobutenyloxy)propyltris(trimethylsiloxane)silane, 3-(isobutenyloxy)propyltrimethoxysilane, 3-methacryloyl... One of the following: oxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltri(b-methoxyethoxy)silane, vinyltriethoxysilane, ethyleneoxytrimethylsilane, vinyldimethylethoxysilane, vinyltri(2-methoxyethoxy)silane, divinyltetramethyldisiloxane, diethoxymethylphenylsilane, diethoxydiphenylsilane, methylphenyldimethoxysilane, p-aminophenyltrimethoxysilane, trimethoxy[3-(phenylamino)propyl]silane, and phenyltriethoxysilane.

[0018] As a preferred embodiment of the aforementioned quantum dot ink, the siloxane is selected from at least one of the following: dodecyltriethoxysilane, cyclohexylethoxysilane, octaphenylcyclotetrasiloxane, dimethylcyclosiloxane, methylsilsesquioxane, tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetraethoxysilane, aminopropyl-containing siloxane, isocyanate-based siloxane, allylsilsesquioxane, tetradecyl dihydroxyheptasiloxane, octamethylcyclotetrasiloxane, methyl vinylcyclosiloxane, methyl phenylcyclosiloxane, trifluoropropylmethylcyclotrisiloxane, methyl vinylcyclosiloxane and dimethylcyclosiloxane, methyl 3,3,5-trifluoropropylsiloxane, phenylsilsesquioxane, and methylsiloxane.

[0019] As a preferred embodiment of the aforementioned quantum dot ink, the organic chain segment is derived from at least one of pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), and tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate;

[0020] Preferably, the organic chain segment in the quantum dot has a weight percentage of 5-80 wt%.

[0021] As a preferred embodiment of the aforementioned quantum dot ink, the acrylate monomer includes at least one of monofunctional acrylate monomers, polyfunctional acrylate monomers, or low-polyacrylate monomers.

[0022] As a preferred embodiment of the aforementioned quantum dot ink, the quantum dot ink contains, by weight percentage, 10-30 wt% quantum dots, 10-30 wt% siloxane, 5-15 wt% reactive coupling agent, 10-90 wt% acrylate monomer, 1-10 wt% photoinitiator, and 1-5 wt% polymerization inhibitor. The inventors have found that this content design results in a suitable quantum dot concentration, minimal self-absorption impact, and high luminous brightness in quantum dot luminescent films made from this quantum dot ink.

[0023] In a second aspect, the present invention provides a quantum dot light conversion element prepared from the above-described quantum dot ink.

[0024] A third aspect of the present invention provides a display device comprising the quantum dot light-emitting film described above.

[0025] Compared with the prior art, the present invention has at least the following advantages:

[0026] 1. The quantum dot ink of the present invention, by adding siloxane to the quantum dot ink, during the process of inkjet printing and curing into a film, the siloxane generates polysiloxane microspheres through a chemical reaction. The polysiloxane microspheres can act as light diffusing agents to improve the optical performance of the quantum dot ink. Thus, in the quantum dot light conversion element formed by the quantum dot ink, the polysiloxane microspheres can scatter the blue light of the backlight source, reduce the transmitted blue light, and allow more blue light to be absorbed by the quantum dots, thereby improving the light output brightness of the quantum dot light conversion element.

[0027] 2. After curing, the quantum dot ink reacts with siloxane to generate polysiloxane microspheres with light diffusion properties. There is no need to add light diffusion particles to the ink. Furthermore, the polysiloxane microspheres are organic materials with low density and are not easy to settle. This avoids the problems caused by adding light diffusion particles, such as the quantum dot ink settling easily in a short time, being difficult to store, and clogging the printhead, which can lead to uneven printing. At the same time, it can significantly improve the light output brightness of the quantum dot light conversion element.

[0028] 3. By adding reactive coupling agents containing C=C bonds and Si-O bonds to quantum dot ink, the organic segments on the surface of quantum dots are linked with photocurable active functional groups. These photocurable active functional groups crosslink with the C=C bonds of the coupling agent, and the Si-O bonds form chemical bonds with siloxanes. This results in excellent dispersion of quantum dots and the formed polysiloxane microspheres in the ink, thereby reducing the surface roughness of the quantum dot light conversion element prepared from quantum dot ink.

[0029] 4. The organic chain segments on the surface of quantum dots are linked with photocurable active functional groups. Under ultraviolet light irradiation and the action of photoinitiator, the photocurable active functional groups undergo cross-linking reaction with acrylate monomers, so that the quantum dots are linked to the acrylate monomers, thereby achieving the purpose of cross-linking quantum dots.

[0030] 5. The photocurable active functional groups on the surface of quantum dots include substituted or unsubstituted propylene groups. Under ultraviolet light irradiation and the action of photoinitiators, the photocurable active functional groups on the surface of the quantum dots crosslink with the acrylate monomers to form chemical bonds. The bonds are strong and the film uniformity is good. Moreover, because the bonds are chemical bonds, the quantum dots will not precipitate from the quantum dot film at high temperatures, ensuring the high luminous efficiency of the quantum dot light-emitting film.

[0031] 6. Because quantum dots and acrylate monomers are chemically bonded, the stability of quantum dots is greatly improved, thus enhancing the water and oxygen resistance of quantum dot films.

[0032] 7. The quantum dots of the present invention have good cross-linking properties with acrylate monomers, the quantum dot concentration is appropriate, and the self-absorption effect is small, thus ensuring the luminous brightness of the quantum dot light conversion element. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Appendix Figure 1 A diagram showing the droplet size when printing the quantum dot ink of Embodiment 1 of the present invention using an inkjet printer;

[0035] Appendix Figure 2 A diagram showing the droplet state when printing the quantum dot ink of Embodiment 1 of the present invention using an inkjet printer;

[0036] Appendix Figure 3 A 100-dot verification image of the quantum dot ink of Embodiment 1 of the present invention printed using an inkjet printer;

[0037] Appendix Figure 4 A printing waveform diagram of printing the quantum dot ink of Embodiment 1 of the present invention using an inkjet printer;

[0038] Appendix Figure 5 This is a scanning electron microscope (SEM) image of the quantum dot luminescent film of Embodiment 1 of the present invention;

[0039] Appendix Figure 6 An atomic force microscope (AFM) image of the quantum dot luminescent film of Embodiment 1 of the present invention;

[0040] Appendix Figure 7 The image shown is a scanning electron microscope (SEM) image of the quantum dot luminescent film in Comparative Example 1.

[0041] Appendix Figure 8 This is an atomic force microscope (AFM) image of the quantum dot luminescent film in Comparative Example 1. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be described in detail below. It should be noted that these embodiments are only partial, not complete.

[0043] As used herein, expressions such as "at least one" modify the entire list of elements without modifying any individual elements of the list when placed before or after it. Unless otherwise defined, all terms in this specification (including technical and scientific terms) are to be defined as commonly understood by one of ordinary skill in the art. Terms defined in common dictionaries should be interpreted as consistent with their meaning in the context of the relevant art and in this disclosure, and should not be interpreted ideally or overly broadly unless clearly defined. Furthermore, unless expressly stated to the contrary, the terms "comprising" and "including," when used in this specification, indicate the presence of the stated features, regions, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or sets thereof. Therefore, the above terms should be understood to mean that the stated elements are included, but not that any other elements are excluded.

[0044] As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items. The term “or” means “and / or”.

[0045] It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms.

[0046] As used herein, “about” or “approximately” includes the stated value and means within an acceptable range of deviation from the specific value, as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the specific quantity (i.e., limitations of the measurement system). For example, “about” may mean a deviation from the stated value within one or more standard deviations, or within ±10%, ±5%.

[0047] As mentioned in the background section, existing quantum dot inks typically incorporate light-diffusing particles to enhance their optical performance. However, the relatively large particle size of these particles can cause uneven printing of the quantum dot ink. Even if the light-diffusing particles are dispersed in the ink, they tend to settle within a short time, resulting in a rough surface on the quantum dot film. This affects the light diffusion effect and consequently the stability of the formed quantum dot luminescent film.

[0048] Based on this, a first aspect of the present invention provides a quantum dot ink comprising quantum dots, a siloxane, and a reactive coupling agent containing C=C bonds and Si-O bonds, wherein the surface of the quantum dots has organic segments, the organic segments are linked with photocurable active functional groups, and the reactive coupling agent is capable of being linked to the siloxane and the photocurable active functional groups.

[0049] This invention adds siloxane to quantum dot ink. During the inkjet printing and curing process, the siloxane reacts chemically to form polysiloxane microspheres. These microspheres act as light diffusing agents, enhancing the optical performance of the quantum dot ink. Consequently, in the quantum dot light conversion element formed from this ink, the microspheres scatter the blue light from the backlight, reducing the amount of transmitted blue light and allowing more blue light to be absorbed by the quantum dots, thus increasing the brightness of the light output. After curing, the siloxane reacts to form light-diffusing polysiloxane microspheres, eliminating the need to add light-diffusing particles to the ink. Furthermore, the polysiloxane microspheres are organic, have low density, and are less prone to settling, avoiding the problems caused by the addition of light-diffusing particles, such as short-term settling, difficulty in preservation, and printhead clogging. This significantly improves the brightness of the quantum dot light conversion element.

[0050] Furthermore, this invention adds a reactive coupling agent containing C=C bonds and Si-O bonds to the quantum dot ink. Since the organic segments on the surface of the quantum dots are linked with photocurable active functional groups, the photocurable active functional groups crosslink with the C=C bonds of the coupling agent, and the Si-O bonds form chemical bonds with the siloxane. This results in excellent dispersion of the quantum dots and the formed polysiloxane microspheres, thereby reducing the surface roughness of the quantum dot light conversion element prepared from the quantum dot ink.

[0051] In one specific embodiment of the present invention, acrylate monomers are also included;

[0052] Preferably, it also includes a photoinitiator;

[0053] Preferably, it also includes a polymerization inhibitor.

[0054] Acrylic monomers are used to disperse and dissolve quantum dots, siloxanes, and reactive coupling agents; photoinitiators play an initiation role in the ink curing process; polymerization inhibitors are used to prevent the aggregation of quantum dots, siloxanes, and reactive coupling agents, resulting in excellent overall dispersion of the quantum dot ink.

[0055] In this invention, the photoinitiator includes at least one of the following: 2,4,6-trimethylbenzoyl-diphenylphosphine, 2-hydroxy-2-methyl-1-phenylpropanone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, benzoin, benzoin dimethyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, benzoin benzoate, benzophenone, 2,4-dihydroxybenzophenone, and micriton.

[0056] In this invention, the polymerization inhibitor includes at least one of the following: butylated hydroxytoluene, hydroquinone, p-methoxyphenol, di-tert-butyl-p-cresol, pyrogallol, tert-butylcatechol, benzoquinone, 4,4'-thiobis(3-methyl-6-tert-butylbenzoic acid), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), N-nitrosophenylhydroxylamine cerium salt, phenothiazine, phenotoxazine, 4-methoxynaphthol, 2,2,6,6-tetramethylpiperidine-1-oxy radical, 2,2,6,6-tetramethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy radical, nitrobenzene, and dimethylaniline.

[0057] In one specific embodiment of the present invention, the photocurable active functional group includes substituted or unsubstituted propylene groups; preferably, the photocurable active functional group is selected from acrylate monomers. That is, the photocurable active functional group contains carbon-carbon double bonds. Under ultraviolet light irradiation and the action of a photoinitiator, the photocurable active functional group on the surface of the quantum dots crosslinks with the acrylate monomers, forming chemical bonds between the quantum dots and the acrylate monomers. The bonds are strong, resulting in good film uniformity. Furthermore, because the bonds are chemical, the quantum dots will not precipitate from the quantum dot film at high temperatures, ensuring the high luminescence efficiency of the quantum dot film.

[0058] In one specific embodiment of the present invention, the reactive coupling agent includes an unsaturated silane coupling agent;

[0059] Preferably, the unsaturated silane coupling agent is selected from methylvinyldimethoxysilane, methacryloyloxyethoxytrimethylsilane, methacryloyloxypropyltris(trimethylsiloxane)silane, γ-methacryloyloxypropyltrimethoxysilane, 1-methoxy-2-methyl-1-(trimethylsiloxy)propene, 3-(methacryloyloxy)propyltrimethoxysilane, 3-(isobutenyloxy)propyltris(trimethylsiloxane)silane, 3-(isobutenyloxy)propyltrimethoxysilane, 3-methacryloyl... One of the following: oxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltri(b-methoxyethoxy)silane, vinyltriethoxysilane, ethyleneoxytrimethylsilane, vinyldimethylethoxysilane, vinyltri(2-methoxyethoxy)silane, divinyltetramethyldisiloxane, diethoxymethylphenylsilane, diethoxydiphenylsilane, methylphenyldimethoxysilane, p-aminophenyltrimethoxysilane, trimethoxy[3-(phenylamino)propyl]silane, and phenyltriethoxysilane.

[0060] In one specific embodiment of the present invention, the siloxane is selected from at least one of dodecyltriethoxysilane, cyclohexylethoxysilane, octaphenylcyclotetrasiloxane, dimethylcyclosiloxane, methylsilsesquioxane, tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetraethoxysilane, aminopropyl-containing siloxane, isocyanate-based siloxane, allylsilsesquioxane, tetradecyl dihydroxyheptasiloxane, octamethylcyclotetrasiloxane, methyl vinylcyclosiloxane, methyl phenylcyclosiloxane, trifluoropropylmethylcyclotrisiloxane, methyl vinylcyclosiloxane and dimethylcyclosiloxane, methyl 3,3,5-trifluoropropylsiloxane, phenylsilsesquioxane, and methylsiloxane.

[0061] In one specific embodiment of the present invention, the organic chain segment is derived from at least one of pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), and tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate;

[0062] Preferably, the organic chain segment in the quantum dot has a weight percentage of 5-80 wt%.

[0063] In one specific embodiment of the present invention, the acrylate monomer includes at least one of monofunctional acrylate monomers, polyfunctional acrylate monomers, or low-functional polyacrylate monomers. Polyfunctional acrylate monomers include difunctional acrylate monomers, trifunctional acrylate monomers, tetrafunctional acrylate monomers, and hexafunctional acrylate monomers.

[0064] In one specific embodiment of the present invention, the quantum dot ink contains, by weight percentage, 10-30 wt% quantum dots, 10-30 wt% siloxane, 5-15 wt% reactive coupling agent, 10-90 wt% acrylate monomer, 1-10 wt% photoinitiator, and 1-5 wt% polymerization inhibitor. The inventors have found that this content design results in a suitable quantum dot concentration, minimal self-absorption impact, and high luminous brightness in quantum dot light conversion elements made from this quantum dot ink.

[0065] Preferably, the monofunctional acrylate monomer is not used alone, but is used in combination with at least one of the following: difunctional acrylate monomer, trifunctional acrylate monomer, tetrafunctional acrylate monomer, hexafunctional acrylate monomer, or low-polyacrylate monomer; while the difunctional acrylate monomer, trifunctional acrylate monomer, tetrafunctional acrylate monomer, hexafunctional acrylate monomer, or low-polyacrylate monomer can be used alone.

[0066] Monofunctional acrylate monomers include: methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, cyclohexyl methacrylate, dicyclopentyl methacrylate, lauryl methacrylate, benzyl methacrylate or phenyl methacrylate, dicyclopentyl (meth)acrylate At least one of the following: HDCPMA, cyclohexyl(meth)acrylate, 4-tert-butylcyclohexyl(meth)acrylate, 3,3,5-trimethylcyclohexyl(meth)acrylate, isobornyl(meth)acrylate, 1-adamantane(meth)acrylate (AMA), 2-adamantane(meth)acrylate, isooctyl(meth)acrylate, isononyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, lauric acid(meth)acrylate (LMA), and stearic acid(meth)acrylate.

[0067] The difunctional acrylate monomers include at least one of the following: tripropylene glycol di(meth)acrylate, tetraethylene glycol dimethacrylate, dimethacrylate, 1,12-dodecadiol 2-methyl-2-acrylate, 1,10-decanediol dimethacrylate, tricyclo[5.2.1.02,6]decanedimethylacrylate, or 1,6-hexanediol diacrylate.

[0068] Trifunctional acrylate monomers include at least one of the following: (ethoxylated)trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, and their analogues.

[0069] Tetrafunctional acrylate monomers include: pentaerythritol tetraacrylate, di(trimethylolpropane)tetraacrylate, and 4(ethoxy)pentaerythritol tetraacrylate; hexafunctional acrylate monomers include dipentaerythritol hexaacrylate.

[0070] This invention preferably uses a mixture of monofunctional and tetrafunctional acrylate monomers, which improves both the degree of crosslinking and the mechanical properties of the quantum dot luminescent film, such as hardness. The content of the monofunctional acrylate monomer is 10–80 wt%, and the content of the tetrafunctional acrylate monomer is 1–20 wt%.

[0071] The quantum dots of the present invention, which have organic chain segments, can be obtained by reacting initial quantum dots with an organic compound to bind the organic compound to the surface of the initial quantum dots. The organic compound comprises the aforementioned organic chain segments and photocurable active functional groups. The reaction temperature between the initial quantum dots and the organic compound is 20-120°C.

[0072] In this invention, the initial quantum dots comprise at least one of group II-VI compounds, group III-V compounds, and perovskite nanocrystals. For example, group II-VI compounds may include: CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgS Te, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, HgZnT eS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe or combinations thereof. Group III-V compounds may include: GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, InZnP, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, or combinations thereof. Perovskite quantum dots include organic perovskite quantum dots and / or inorganic perovskite quantum dots, which may be commercially available products.

[0073] The initial quantum dots were prepared using existing solution-based preparation techniques, followed by purification, and will not be elaborated here.

[0074] A second aspect of the present invention provides a quantum dot light conversion element prepared from the aforementioned quantum dot ink. The quantum dot ink is inkjet printed, followed by photocuring and heat treatment to form the quantum dot light conversion element. During the curing and heat treatment process, the siloxane undergoes a hydrolytic polymerization reaction to generate polysiloxane microspheres with light diffusion properties. Simultaneously, during the curing and heat treatment process, the unsaturated silane coupling agent undergoes hydrolysis and dehydration condensation, forming covalent bonds with the quantum dots, acrylates, and siloxane, thereby reducing the surface tension of the quantum dot luminescent film, reducing the film surface roughness, and ensuring the stiffness and stability of the film surface.

[0075] In one specific embodiment of this application, the heat treatment temperature is between 25°C and 110°C, preferably between 80°C and 100°C, thereby effectively controlling the particle size of the self-generated polysiloxane microspheres within a suitable range. Preferably, at least part of the heat treatment is completed in a water-vapor-containing environment. This environment allows the siloxane to undergo hydrolysis and polymerization under slightly aqueous conditions, generating polysiloxane microspheres with light-diffusing properties. The water-vapor-containing atmosphere can be an air atmosphere. In an air atmosphere, the siloxane undergoes hydrolysis and polymerization during curing to form polysiloxane microspheres. This simplifies the production equipment requirements, eliminating the need for high-temperature and high-pressure equipment, and effectively simplifying the production process of the quantum dot luminescent film. Under these conditions, the saturated silane coupling agent simultaneously undergoes a hydrolysis-condensation reaction, grafting quantum dots, siloxane, and acrylate monomers, thereby improving the roughness of the quantum dot luminescent film.

[0076] A third aspect of the present invention provides a display device comprising the aforementioned quantum dot luminescent film. The display device of the present invention includes any product or component with display function, such as electronic paper, mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, navigator, in-vehicle display, AR display, VR display, etc. Due to the use of the aforementioned quantum dot luminescent film, the display device of the present invention exhibits excellent light emission performance. In addition to the aforementioned quantum dot luminescent film, the display device of the present invention may also include structures known to those skilled in the art, such as electroluminescent diodes, touch panels, and encapsulation covers.

[0077] Some exemplary embodiments of the present invention are described in more detail below; however, the exemplary embodiments of the present invention are not limited thereto.

[0078] Example 1

[0079] S1. Preparation of quantum dots:

[0080] 100 mg of green CdZnSeS / ZnS quantum dots and 10 mg of pentaerythritol tetra(3-mercaptopropionate) were added to 1 ml of xylene and reacted at 80 °C under nitrogen for 60 minutes. Then, 8 mg of acrylic acid-acrylate copolymer was added and reacted at 60 °C for 60 minutes. After vacuum drying to remove xylene, quantum dots with organic segments and propylene groups linked to the organic segments were obtained.

[0081] S2. Preparing quantum dot ink:

[0082] Based on the total weight of the quantum dot ink, 25 wt% of the above-mentioned quantum dots with organic segments and propylene groups linked to the organic segments, 16 wt% of triethylene glycol dimethacrylate, 19 wt% of 1,10-decyl glycol dimethacrylate, 3 wt% of pentaerythritol tetraacrylate, 22 wt% of dodecyltriethoxysiloxane, 5 wt% of photoinitiator TPO-L (ethyl 2,4,6-trimethylbenzoylphenylphosphonate), 1 wt% of polymerization inhibitor BHT (butylated hydroxytoluene), and 9 wt% of 3-[tris(trimethylsiloxy)silyl]propyl methacrylate are mixed evenly to obtain the quantum dot ink.

[0083] The quantum dot ink from Example 1 was inkjet printed using an OmniJet-500 GB inkjet printer (printhead model: Samba cartridge). The printing results are as follows: Figure 1-4 As shown, from Figure 1 The droplet size (3.8 pl) plot, and Figure 2 The state of droplets in inkjet printing and Figure 3 The 100-dot verification chart shows that the ink droplets are small and do not overlap, enabling high-quality printing; from Figure 4 The print waveform shows that the printing is smooth and suitable for inkjet printing at a relatively high speed.

[0084] After inkjet printing with quantum dot ink in Example 1, a curing heat treatment was performed to obtain a quantum dot light conversion element. Under a scanning electron microscope, it can be seen that... Figure 5 The quantum dot optical conversion element shown has many self-generated polysiloxane microspheres on its film surface (white dots in the image represent polysiloxane microspheres). It can be seen that the particle size of the polysiloxane microspheres is between 20 and 50 nm, exhibiting small size and uniform particle size. Figure 6 The surface morphology and surface roughness morphology of the quantum dot light conversion element film are given. It can be seen that the difference between the highest and lowest points of the film surface is small (-42.9nm~38.0nm), and the film surface of the entire quantum dot light conversion element is relatively dense and very uniform and flat.

[0085] Comparative Example 1

[0086] S1. Preparing quantum dot ink:

[0087] Based on the total weight of the quantum dot ink, 25 wt% of green CdZnSeS / ZnS quantum dots (surface ligands are bis(p-chlorophenyl)trichloroethane, oleylamine, and oleic acid ligands), 20 wt% of triethylene glycol dimethacrylate, 24 wt% of 1,10-decanediol dimethacrylate, 3 wt% of pentaerythritol tetraacrylate, 22 wt% of dodecyltriethoxysiloxane, 5 wt% of photoinitiator TPO-L (ethyl 2,4,6-trimethylbenzoylphenylphosphonate), and 1 wt% of polymerization inhibitor BHT (butylated hydroxytoluene) were mixed evenly to obtain the quantum dot ink.

[0088] After inkjet printing with the quantum dot ink from Comparative Example 1, a curing heat treatment was performed to obtain a quantum dot optical conversion element. Under a scanning electron microscope, it can be observed that... Figure 7 Although the quantum dot light conversion element shown has many self-generated polysiloxane microspheres on its film surface, the particle size of these microspheres is quite large, ranging from 300 to 600 nm, and the film surface contains numerous pores. Figure 8 The surface morphology and surface roughness morphology of the quantum dot light conversion element film are given. It can be seen that the difference between the highest and lowest points of the film surface is relatively large (-375.1nm~264.9nm), and the film surface of the entire quantum dot light conversion element is relatively rough.

[0089] The quantum dot light conversion elements of Example 1 and Comparative Example 1 were illuminated with a blue backlight. The brightness of the green light emitted by Example 1 and Comparative Example 1 and the absorption rate of the blue light were tested using an optical color analyzer. The testing equipment was a PR-670 fluorescence spectrometer and the backlight intensity was 1000 nits. The results are shown in Table 1 below.

[0090] Table 1

[0091] project QD total brightness cd / m2 Light output brightness (cd / m2) Blue light absorption rate % Example 1 2125.5 2071.9 94.7 Comparative Example 1 2118.1 2002.2 87.9

[0092] As shown in Table 1, the quantum dot light conversion element prepared by the quantum dot ink of Example 1 of the present invention can obtain better light output brightness than that of Comparative Example 1. It can be seen that the present invention adds an unsaturated silane coupling agent to the quantum dot ink, which makes the quantum dots more dispersed, and the prepared quantum dot light conversion element has higher light output brightness, better light conversion effect and better light emission performance.

[0093] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A quantum dot ink, characterized in that, The mixture includes quantum dots, siloxanes, reactive coupling agents containing C=C and Si-O bonds, and acrylate monomers. The surface of the quantum dots has organic segments linked to photocurable active functional groups. The reactive coupling agent can connect to the siloxane and the photocurable active functional groups. The photocurable active functional groups include substituted or unsubstituted propylene groups. The reactive coupling agent includes unsaturated silane coupling agents. The organic segments are derived from at least one of pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), and tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate.

2. The quantum dot ink according to claim 1, characterized in that, It also includes photoinitiators and polymerization inhibitors.

3. The quantum dot ink according to claim 1, characterized in that, The unsaturated silane coupling agent is selected from one of the following: methylvinyldimethoxysilane, methacryloyloxyethoxytrimethylsilane, methacryloyloxypropyltris(trimethylsiloxane)silane, γ-methacryloyloxypropyltrimethoxysilane, 1-methoxy-2-methyl-1-(trimethylsiloxy)propene, 3-(methacryloyloxy)propyltrimethoxysilane, 3-(isobutenyloxy)propyltris(trimethylsiloxane)silane, 3-(isobutenyloxy)propyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltris(b-methoxyethoxy)silane, vinyltriethoxysilane, ethyleneoxytrimethylsilane, vinyldimethylethoxysilane, vinyltris(2-methoxyethoxy)silane, and divinyltetramethyldisiloxane.

4. The quantum dot ink according to claim 1, characterized in that, The siloxane is selected from at least one of the following: dodecyltriethoxysilane, cyclohexylethoxysilane, octaphenylcyclotetrasiloxane, dimethylcyclosiloxane, methylsilsesquioxane, tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetraethoxysilane, aminopropyl-containing siloxane, isocyanate-based siloxane, allylsilsesquioxane, tetradecyl dihydroxyheptasiloxane, methyl vinylcyclosiloxane, methyl phenylcyclosiloxane, trifluoropropylmethylcyclotrisiloxane, methyl-3,3,5-trifluoropropylsiloxane, phenylsilsesquioxane, and methylsiloxane.

5. The quantum dot ink according to claim 1, characterized in that, In the quantum dots, the organic chain segments comprise 5-80 wt% by weight.

6. The quantum dot ink according to claim 2, characterized in that, The acrylate monomers include at least one of monofunctional acrylate monomers, polyfunctional acrylate monomers, or low-functional polyacrylate monomers.

7. The quantum dot ink according to claim 2, characterized in that, In the quantum dot ink, by weight percentage, the content of quantum dots is 10-30 wt%, the content of siloxane is 10-30 wt%, the content of reactive coupling agent is 5-15 wt%, the content of acrylate monomer is 10-90 wt%, the content of photoinitiator is 1-10 wt%, and the content of polymerization inhibitor is 1-5 wt%.

8. A quantum dot light conversion element, characterized in that, It is prepared from the quantum dot ink according to any one of claims 1-7.

9. A display device, characterized in that, Includes the quantum dot light conversion element as described in claim 8.

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